Aerial apparatuses such as turnable ladders of fire-fighting vehicles are controlled by an operator from a position giving him an overview of the space in which the aerial apparatus is moved. For reason of simplicity the further description will refer to turnable ladders as one example of aerial apparatuses, although this example is not to be understood as limiting in the sense of the present invention. As it is commonly known, such turnable ladders can be turned around a vertical axis and also extracted, as well as lowered or lifted, to reach remote positions in rescue situations. It is very important to reach this remote points as fast as possible so that no time needed for the rescue of persons, etc. is lost. On the other hand, the movement speed of the turnable ladder is limited by construction parameters and also depending on its present position, especially its extension range. All these parameters cannot be overviewed by the operator in the rescue situation.
A common control station of a turnable ladder is generally provided with a manually operable input device, such as a control lever or joystick, which is deflectable in at least one spatial direction by a deflecting force applied by the operator. For example, a joystick allows to input direction and moving speed of a turnable ladder. A processing unit converts the amount of deflection of the input device into a corresponding speed signal, which is transferred to an actuating unit for moving the aerial apparatus with a speed corresponding to the speed signal.
To assist the operator in controlling the turnable ladder, systems are known with comprise sensors, for example, distance sensors at the end of the ladder to generate a warning signal to avoid a collision with an object. Other kinds of sensors protect against overloading. However, the generation of warning signals or the execution of a forced shut down of the system is only an incomplete assisting function to control the movement of the ladder. In particular there is a desire to control the ladder at maximum moving speed depending on the present situation. However, even in the presents of sensors that generate warning signals or prevent the ladder from a collision or overload, the control of the ladder still demands a control of a experienced operator and much skill to be operated in difficult situation, for example, at maximum range in a narrow space.